What does my coolant temp sensor control exactly?

[turblu]

What does the coolant temp sensor control? I am having irratic idles as well as hesitation. Does this have something to do with it?

[S13FASTBACKSR]

probably not the coolant temp sensor..the coolant temp sensor tells the ecu the temperature of the engine which in turn the ecu puts the correct amount of fuel needed into the engine...if you have a bad coolant temp sensor then say your engine is warm and you shut it off then 5 seconds later try to start it...the sensor being bad will tell the ecu the engine is cold which in turn the ecu will tell the injectors to put more fuel in to start the engine because its cold (where as its really warm so too much fuel will flood it) see what i mean?

your problem sounds like timing, the gap in your spark plugs are wrong..maybe something to do with injectors or maf or a vaccuum leak..are you running rich at all?